Method of mechanical separation for a double layer transfer

Abstract

The present disclosure relates to a method for mechanically separating layers, in particular in a double layer transfer process. The present disclosure relates more in particular to a method for mechanically separating layers, comprising the steps of providing a semiconductor compound comprising a layer of a handle substrate and an active layer with a front main side and a back main side opposite the front main side, wherein the layer of the handle substrate is attached to the front main side of the active layer, then providing a layer of a carrier substrate onto the back main side of the active layer, and then initiating mechanical separation of the layer of the handle substrate, wherein the layer of the handle substrate and the layer of the carrier substrate are provided with a substantially symmetrical mechanical structure.

What is claimed is: 
     
       1. A method for mechanically separating layers, comprising the steps of:
 providing a first compound structure comprising a layer of material having a first main side and a second main side opposite to the first main side, and a first substrate on the first main side of the layer of material; then 
 attaching a second substrate onto the second main side of the layer of material such that the layer of material is disposed between the first substrate and the second substrate; and then 
 thinning the first substrate so as to form a substantially symmetrical mechanical structure upon completion of the thinning of the first substrate; and then 
 initiating mechanical separation of the layer of the first substrate so as to obtain another compound structure comprising the second substrate and the layer of material, 
 wherein the substantially symmetrical mechanical structure comprises the layer of material, a thinned first substrate on the first main side of the layer of material, and the second substrate on the second main side of the layer of material, and wherein the thinned first substrate on the first main side of the layer of material has substantially the same mechanical properties as the second substrate on the second main side of the layer of material. 
 
     
     
       2. The method of  claim 1 , wherein thinning the first substrate comprises selecting a thickness of the first substrate such that a product of the thickness (t 1 ) of the first substrate and a Young's modulus (E 1 ) of the first substrate (E 1 t 1   3 ) and a product of a thickness (t 2 ) of the second substrate and a Young's modulus (E 2 ) of the second substrate (E 2 t 2   3 ) are within about 20% or less of one another. 
     
     
       3. The method of  claim 2 , wherein E 1 t 1   3  and E 2 t 2   3  are equal. 
     
     
       4. The method of  claim 1 , wherein the second substrate has a chamfered edge. 
     
     
       5. The method of  claim 1 , wherein the second substrate comprises a homogeneous high resistivity material. 
     
     
       6. The method of  claim 1 , wherein the second substrate has a resistivity of at least 10 kΩ·cm. 
     
     
       7. The method of  claim 1 , wherein the second substrate comprises:
 a support layer; and 
 at least one layer of a high resistivity material on the support layer, the at least one layer of the high resistivity material disposed between the layer of material and the support layer. 
 
     
     
       8. The method of  claim 7 , wherein the at least one layer of high resistivity material is in direct physical contact with the layer of material. 
     
     
       9. The method of  claim 7 , further comprising, before the step of initiating mechanical separation, a step of replicating the at least one layer of a high resistivity material on the first substrate. 
     
     
       10. The method of  claim 9 , wherein the step of replicating the at least one layer of the high resistivity material on the first substrate comprises replicating the at least one layer of the high resistivity material on a free side of the first substrate opposite the layer of material. 
     
     
       11. The method of  claim 7 , wherein the support layer comprises silicon. 
     
     
       12. The method of  claim 7 , wherein the at least one layer of a high resistivity material has a thickness of from 30 μm to 200 μm. 
     
     
       13. The method of  claim 7 , wherein the at least one layer of a high resistivity material has a resistivity of at least 10 kΩ·cm. 
     
     
       14. A wafer structure, comprising:
 a first substrate having a first thickness (t 1 ) and exhibiting a first Young's modulus (E 1 ); 
 a layer of a first material attached to the first substrate; and 
 a second substrate having a second thickness (t 2 ) and exhibiting a second Young's modulus (E 2 ) the second substrate attached to the layer of the first material such that the layer of the first material is disposed between the first substrate and the second substrate, 
 wherein the first thickness is different than the second thickness or the first Young's modulus is different than the second Young's modulus, 
 wherein a product of the first Young's modulus and the first thickness cubed (E 1 t 1   3 ) and a product of the second Young's modulus and the second thickness cubed (E 2 t 2   3 ) are within about 20% or less of each other. 
 
     
     
       15. The wafer structure of  claim 14 , wherein the second substrate comprises a high resistivity material. 
     
     
       16. The wafer structure of  claim 15 , wherein the first substrate comprises silicon. 
     
     
       17. The wafer structure of  claim 14 , further comprising a layer of an oxide material disposed between the layer of the first material and the second substrate. 
     
     
       18. The wafer structure of  claim 14 , wherein the first substrate is not in direct contact with the second substrate. 
     
     
       19. The wafer structure of  claim 14 , wherein the second substrate comprises a multi-layer substrate. 
     
     
       20. The wafer structure of  claim 14 , wherein the first substrate comprises a first support layer and at least one first layer of a high resistivity material attached to the first support layer, the second substrate comprises a second support layer and at least one second layer of a high resistivity material attached to the second support layer, the layer of the first material attached to the first support layer of the first substrate and the at least one second layer of a high resistivity material of the second substrate.